NEW DELHI, India (CNN) -- India on Wednesday rejected any third-country mediation in its relationship with arch-rival Pakistan, a day after the U.S. and Chinese presidents pledged cooperation on South Asian issues.

"A third-country role cannot be envisaged nor is it necessary," India's external affairs ministry said in a statement here.

The statement cited a 1972 pact with Pakistan on the U.N.-enforced military line of control that still divides the Kashmir region that both countries claim.

The Indian government said it was committed to resolving all outstanding issues bilaterally with Pakistan in accordance with the 37-year-old Simla Agreement.

"We also believe that a meaningful dialogue with Pakistan can take place only in an environment free from terror or the threat of terror," it added.

In their joint statement on Tuesday, U.S. President Barack Obama and his Chinese counterpart Hu Jintao vowed support to moves aimed at improving ties between India and Pakistan.

"The two sides (the United States and China) are ready to strengthen communication, dialogue and cooperation on issues related to South Asia and work together to promote peace, stability and development in that region," they said.

In his remarks at a news conference shortly before the Indian reaction to the Beijing statement, Timothy J. Roemer, the U.S. ambassador to India, described the current status of relations between New Delhi and Washington as "unparalleled" and "unprecedented."

He said his country stands beside India "shoulder-to-shoulder" and "hand-in-hand" especially in its counterterrorism efforts.

Indian Prime Minister Manmohan Singh travels to the United States this weekend on a key state visit.

Last year's Mumbai terror attacks that left more than 160 people dead, including six Americans, are likely to figure in his talks with President Obama, Roemer said.

India blames militant groups based in Pakistan for the three-day siege of its financial capital.

Both leaders are also expected to discuss the Afghanistan-Pakistan strategy when they meet for what Roemer called would be "rich, robust and deep" discussions.